Data Radio

Data Radios

Hello everyone, We are currently looking at purchasing approximately 500 radios for the purposes of SCADA data acquisition. The simplified requirements for these radios are:

- 150 MHZ band, preferrably software programmable.

- 25 KHz channel spacing, 12.5 KHz preferrably.

- 9600 bps

- Key-on delay: up to 13 milliseconds

- Maximum error rate: 1 bit out of 10^6 bits

- Capable of asynchronous or synchronous communication, preferrably both

- RS232 interface with standard modem signals (RTS, CTS, DCD, clocks, etc). What is your experience with such radios, can you recommend any vendors? All responses (including from vendors) would be appreciated. Thank-you all.

 /francois
 francois@cae.ca
 Systems Analyst, CAE Electronics Ltd.

Re: Data Radios

Hello Everyone: On Tue, 15 Apr 1997 09:33:14 -0700, Francois Mathieu wrote: I work in marketing at DATARADIO, a major manufacturer of data-by-radio products in Montreal. Our COR (Connectivity-Over-Radio) product line is used in SCADA applications. You can find out all about our company and products at: http://www.dataradio.com Francois, we have a wide range of products that could suit your needs. Detailed technical specs are available online. If you don't have Web access, contact me directly and I'll provide you with more info, and refer you to my boss who has a more technical background than myself. He will likely contact you in any case. Sincerely,

 Allen Mendelsohn
 DATARADIO Inc.
 5500 Royalmount, Suite 200
 Town of Mount Royal, Quebec
 CANADA
 H4P 1H7
 (514) 737-0020
 fax (514) 737-7883
 amendelsohn@dataradio.com
 http://www.dataradio.com

Re: Data Radios

You may be interested in looking at the Motorola Darcom data radio equipment, it conforms to all the above requirements with the possible exception that it may not be available in the frequency band you mentioned. We use Darcom equipment in the 853 - 949 MHz band with good success.

 -----------------------------------------------------------------------------
 Patrick Collins - Load Survey Technician           email : pc012@seqeb.gov.au
 South East Queensland Electricity Corporation      phone : +61 7 3407 5954
 Blinzinger Rd, Banyo, 4014                         fax   : +61 7 3407 5454
 Queensland, AUSTRALIA (Best State, Best Country)   Viva el Cristo Rey !
 -----------------------------------------------------------------------------

Re: Data Radios

We are using Radio Modems from Satel in Finland in a Siemens PLC network. Some data from brochure:

 Type: Satelline-2ASx
 Frequency Range: 405-470 Mhz
 Channel Separation: 25Khz (also 20kHx/12.5kHz)
 
 Data Interface: RS-232
 Baud Rate: 9600

 SATEL
 P.O.Box 142
 FIN-24101 Salo Finland
 Fax: +358-24-331034

 Agust H. Bjarnason,   agust@rt.is   http://www.rt.is
 RT Ltd
 Iceland

Re: Data Radios

Hi Patrick, 2 quick questions:

1. What is the max data rate that you can reliably push accross the Darcom radios

2. Is the modulation GMSK Cheers

 Don Ingram
 dingram@m130.aone.net.au
 Ph +61 79 546074
 Fx +61 79 546668

Re: Data Radios

Don; I'd like to answer the questions if I may: Dataradio, aside from being a manufacturer of telemetry radios, also is the worldwide master distributor for Motorola's RNet telemetry radio and radio-modem product line. As such we are extremely familiar with all of the Motorola product lines including both the DARCOM and MOSCAD

Ref: c:\scada\041997\msg00006.xml

(Fwd) Re: Redundant Radios Hook-up to single antenna

Redundant Radios Should be a simple thing to make an RF controlled relay switching circuit that could control a co-axial relay to switch the antenna between the two radios. That way when the radio starts transmitting the RF controlled switching circuit would detect the transmitted power and switch over the antenna to that radio. If the same number of relays were used as the number of radios then each radio could have a termination resistor (50 ohm load) which is normally switched onto it's output by the relay being non-energised. When the relay is energised it could connect the radio to the antenna system. Regards

Ref: c:\scada\061997\msg00001.xml

(Fwd) Re: Redundant Radios Hook-up to single antenna

Hello Francois, On the dual radio question, you may use a coax relay, or perhaps better would be a duplexer. The relay adds a solenoid and contact that become additional failure points in the system. The duplexer does not, as it is a passive device. Don't forget that the oustide system is also very subject to failure, the feedline, connectors, and antenna. So, you must consider the expense of dual radios versus your actual savings in downtime. In severe climates, it is better to also have dual lines and antennae. Regards, Bill Cross CrosStar

Ref: c:\scada\061997\msg00002.xml

Re: Redundant Radios Hook-up to single antenna

Francois; We've been down that road a number of times here at Dataradio. Dow Key makes coaxial transfer relays (among others). They have a number of different configurations and coil voltages. Available options include auxiliary contacts so that you can confirm the switchover or transfer power from the primary to the secondary radio without bothering about having to 'build out' the signal - and there are other manufacturers as well. I don;t think anyone makes a relay that is directly controlled by an RS-232 signal, but that's a simple problem to resolve. If you want, I can look into sources of supply - there are a couple of industrial catalog houses like Allied in the 'states who have them in their catalogues. regards

 Bram Frank
 Director of Sales
 --------------------------------------------------------------------------
      Tel: +1 514 737-0020        Post: Dataradio Inc.
      Fax: +1 514 737-7883              5500 Royalmount Avenue, Suite 200
                                        Montreal, Canada
   e-mail: bfrank@dataradio.com         H4P 1H7
 Web page: http://www.dataradio.com

Re: Redundant Radios Hook-up to single antenna

Dear Francois, The most simple solution would be to use a 'hot standby wired' coax relay. Coax relays can be obtained at any whole sale shop of electronic components such as RS-Components, MAPLIN, etc. One of the more famous makes that springs to my mind is DOWKEY. They produce high quality relays up to GHz range. If you add proximity switches on the same relay so you can even get mechanical confirmation of the coax switch operation. Wire up the relay coil to one of your binary output ports in such way that when power disappears the fall back will be your redundant radio. Best regards

 Trond Thorman
 RADIUS Technology
 Radio Data and Telemetry Specialist, SCADA Integration

Re: Redundant Radios Hook-up to single antenna

A relay is likely the only way to go. Remember that this is a SAME FREQUENCY redundant radio application. As such a duplexer will not be useable because there is no way to route the signals on the basis of frequency - which is what a duplexer does. ....stuff snipped........ A good point. I have always argued against 'hot standby' systems because the link between the host and master radio, if run by leased line and modem is orders of magnitude more likely to fail than the radio - and a failure in the antenna system (due to a lightning strike or windstorm) is also not dealt with by the HST packages. Of course the sophisticated failure monitoring system adds complexity and increases the likelihood of a failre due to the supervisory system - and a physically common redundant radio will more likely be damaged along with the primary if a lightning strike takes out the system. The ideal mechanism is to completely duplicate the transmission system using two host ports, two phone lines with separate modems and two antenna systems physically separated. The application should switch all comms to the backup serial port in the event of a failure - it should drop carrier on the primary port as well to eliminate traffic from the primary site as well. regards to all

 Bram Frank
 Director of Sales
 --------------------------------------------------------------------------
      Tel: +1 514 737-0020        Post: Dataradio Inc.
      Fax: +1 514 737-7883              5500 Royalmount Avenue, Suite 200
                                        Montreal, Canada
   e-mail: bfrank@dataradio.com         H4P 1H7
 Web page: http://www.dataradio.com

Re: Redundant Radios Hook-up to single antenna

Maplin and RS-Components are UK-specific vendors - companies in North America that do this kind of stuff have been falling like flies lately. Several, such as Allied are still in business though. º If you add proximity switches on the same relay so you can even get º mechanical confirmation of the coax switch operation. º Wire up the relay coil to one of your binary output ports in such way that º when power disappears the fall back will be your redundant radio. I agree - I hadn't thought about wiring the relay in PFAIL mode - good idea! If you do this and if the equipment is operated using DC coils, make certain that coil polarity is periodically reversed or the relay exercised because they will magnetize over time and may not drop out on power removal. Remember that if there is a failure, the binary port may not change state. A more traditional approach is to use the backup unit to handle the transfer. If operated using dual modems and phone lines, but a common antenna, the DCD lead on the BACKUP modem could be used to initiate the transfer. again, regards to all

 Bram Frank
 Director of Sales
 --------------------------------------------------------------------------
      Tel: +1 514 737-0020        Post: Dataradio Inc.
      Fax: +1 514 737-7883              5500 Royalmount Avenue, Suite 200
                                        Montreal, Canada
   e-mail: bfrank@dataradio.com         H4P 1H7
 Web page: http://www.dataradio.com

Re: Redundant Radios Hook-up to single antenna

RF controlled relays would be a liability without some serious logic to prevent a runaway transmitter from switching TWO users to the antenna. The typical SPDT RF relay arrangement precludes using a resisitive termination load and preventing this type of problem unless you use TWO relays per radio in addition to the lockout logic. Switching the power to the backup radio OFF on transfer will prevent problems of this type. A good point about termination though. Hot standby means just that. The backup transmitter is actively transmitting and it's RF is being sunk by a shielded load resistor. It is switched into service instantaneously in the event of a detected failure. But Francois' question was about 'redundant radios' and not Hot Standby. His system might even operate using a switched simplex radio - note that such switched simplex applications cannot use host standby radios under any condition that I am aware of. I think that the most reliable solution is the simplest. Less stuff to break. Again - regards

Bram Frank
 Director of Sales
 --------------------------------------------------------------------------
      Tel: +1 514 737-0020        Post: Dataradio Inc.
      Fax: +1 514 737-7883              5500 Royalmount Avenue, Suite 200
                                        Montreal, Canada
   e-mail: bfrank@dataradio.com         H4P 1H7
 Web page: http://www.dataradio.com
 

Re: Redundant Radios Hook-up to single antenna

At 11:27 AM 6/10/97 -0700, you wrote: A number of possible solutions have been suggested. It is hard to know just what is best with out knowing more about your system.

- Are you running simplex or a split pair - separate rx / tx frequencies?

- What frequency range are you operating in?

- If your using a split pair do you want both receivers always connected?

- HOW MUCH LOSS can your antenna system handle with out degrading system performance?

- How fast does the system have to switch?

Likely the simplest solution is to use a relay. I highly recommend the DowKey products as I they have performed well for me in the past. They are the cheapest, but if you going through all this trouble don't go cheap here.

The DowKey relays typically are spec'd around a 0.1dB through port loss ( some one correct me if they've improved on this ). Make sure that the model you use switches the unused TX to a terminator of sufficient power handling capabilities to match your transmitter.

Keep in mind that relays don't last for ever. Avoid switching while the radio is transmitting. Switches are available to handle this abuse, but your transmitter may not. A low quality switch may 'weld' its contacts. Expect loss to increase with age as well on particularily on lower quality devices.

In some instances you can also use a solid state switch. Typically these are used in the 800Mhz and up range ( lower frequencies make the strip lines less practical ). You see this approach in some cold/warm/hot standby radio systems. The good news is that you can switch these very quickly. The bad new is that power handling capabilities are limited - at least for most people's budgets. These devices tend to be product specific, but DowKey or the equiv. may be able to supply a device.

There is another method that I've used on a limited basis and that's a circulator. To get sufficient isolation you typically have to be able to live with a higher losses in the antenna system (particularily at lower frequencies). The trade off on the plus side is no moving parts or control requirements. It would be best to talk to an 'antenna system' specialist or quailified supplier. I have had good support in the past from Sinclair's engineering support staff.

It was also suggested that you could use redundant antennas. On the surface its a great idea, but it opens a can of worms. If you are lucky enough to be in a location with no other transmitters and a sufficiently tall tower you can gain some vertical isolation between antennas with out effecting your required coverage. For the rest of the world you are increasing the risk of intermod ( I wouldn't go into all this here, but in short the opposing transmitter's PA is an on frequency non-linearity therefore a fine mixer ). The bottom line is that you still need to provide some sort of isolation between systems. Thats not to say you can't do it, but for the sake of diplomacy with other co-located radio users, hire your self a reputable radio site engineer.

One last thought... before you go through all this trouble, make sure this is your weak link. I've seen more than one redundant system crash because of one wire or a single power source.

 -------------------------------------------------------------------------
   Bill Erlenbach, A.Sc.T.                     E-Mail berlenba@direct.ca  
   Telesphere Communications                   Tel 604-990-3598  
   Corporation                                 Fax 604-929-7717
   North Vancouver, B.C., Canada                           
 -------------------------------------------------------------------------

Ref: c:\scada\061997\msg00014.xml

FW: Redundant Radios Hook-up to single antenna

Bill Just a note regarding the coaxial relay solution. I do not know what the RF output power is on your radios, but remember that it is not wise to leave high power RF amplifiers un-terminated (hot standby transmitter)! It is normal practice to include a circulator (with dummy load on the third port) between the amp and coaxial relay in order to dissipate power that is reflected from the un-terminated coaxial relay port. Alternatively you may use a coaxial 'transfer switch' which is a 4-port device. The fourth port is connected to a dummy load and ensures that the standby transmitter (regardless of whether it is the A or B transmitter) is always terminated in a matched load. Transfer time for such switches is normally 20 ms or better (same for coaxial relays).

 Regards
 Kevin Humphreys
 Senior Communications Engineer, Sinclair Knight Merz

Ref: c:\scada\061997\msg00015.xml

GE RF Radios - details

Hello again Many Thanks to Trond Thorman, Bill Cross and Bram Frank, it is great help. Following Trond Thorman suggestion, enclosed further details, as far as the client give us:

0. GE stands for General Electric, sorry

1. Frequency VHF/UHF

2. Interface speed 9600 - 19200

3. Air speed 2400 - 9600

4. Distance is up to 30 km radius

5. We need few repeaters, most of the stations does not

6. We do not need full-duplex

7. Client take care of licensing

8. In some site we need 25w RF power. Can a booster do the job with the above configuration?

Thank you all
 
 Moshe Sela
 Cabri, Israel
 selamo@cabri.org.il

Re: GE RF Radios - details

I believe that EF Johnson also makes a data radio, but do not have details. They have an office here in Minneapolis. Try an address at www.johnsondata.com Bill Cross

Re: GE RF Radios - details

I prefer to run the thread in reverse chrono order so this entry is at the head: E.F. Johnson have gotten out of the telemetry radio business. The telemetry division was purchased by our company (Dataradio Inc., of Montreal) last February and we operate it as a subsidiary, FYI. Dataradio manufactures it's own line of analogue and 1200-9600 bps radio- modems and packet modems in addition to serving as Motorola's master distributor for their RNet product line - so we have a lot of bases covered with VHF, UHF, 900 MHz and 'no radio' (for locations where the standards don't work) radio-modems and modem controllers. The diversity is reflected in the range of prices. Dataradio is a trademarked name, it has been since 1981 - Bill aluded to the fact that GE/Ericsson have a product that might infringe on our copyright - Bill, would you have access to proof of their use of our name on one of their products? Thanks to all and best regards.

 Bram Frank
 Director of Sales
 --------------------------------------------------------------------------
      Tel: +1 514 737-0020        Post: Dataradio Inc.
      Fax: +1 514 737-7883              5500 Royalmount Avenue, Suite 200
                                        Montreal, Canada
   e-mail: bfrank@dataradio.com         H4P 1H7
 Web page: http://www.dataradio.com

Re: GE RF Radios - details

Bram: I do not any longer have literature from GE, but recall a product called "Dataradio" in the 80's. It was a small, well shielded box like today's modem, and had connectors suitable for OEM use, instead of the usual mic and speaker. Perhaps my recollection of the name is incorrect, a lot of time has gone by. It was a VHF and UHF crystal radio. I'm afraid you have to take it from there, but its probably a no win trail. I haven't seen one for many years. Bill Cross CrosStar

Re: GE RF Radios - details

Bill Thanks for the news. Your information might describe their old DL-100 which was based on their original PY series walkie Talkie. It was an analog portable radio stuffed into an enclosure and suitable for up to 1200 baud (202) modems. They may still make it, but then the Paging group at Ericsson is using our radio-modems for their applications now, so I would doubt it. Thanks again and regards

 Bram Frank
 Director of Sales
 --------------------------------------------------------------------------
      Tel: +1 514 737-0020        Post: Dataradio Inc.
      Fax: +1 514 737-7883              5500 Royalmount Avenue, Suite 200
                                        Montreal, Canada
   e-mail: bfrank@dataradio.com         H4P 1H7
 Web page: http://www.dataradio.com

Ref: c:\scada\051997\msg00004.xml

Re: Microwave Equipment Supply

Also try Cyplex represented by CD Nova in Vancouver, British Columbia for digital microwave at about 5Ghz. --

 John Cooke, P. Eng., Improvement Team Project Manager
 http:\\WWW.EPCOR-GROUP.COM   EPCOR Utilities Inc.
 8743-58 Avenue, Edmonton, Alberta, T6E 5W4, CANADA
 Voice 403-448-3206 Fax 448-3250 Cel 940-2176 EMail
 jcooke@epcor-group.com

Ref: c:\scada\061997\msg00008.xml